Research articles

Not available – first paragraph follows:
Until recently, UC Cooperative Extension has addressed itself to all phases of agricultural production and processing but has virtually ignored the social problems of farm labor. For the past five years, however, with funding from the Expanded Nutrition Education Program (ENEP) and Community Resources Development (CRD), increasing emphasis has been given to this area. One of the first pilot programs implemented was to provide outdoor education for migrant children enrolled in summer schools in Region I, Office of Migrant Education. The program was initiated in the summer of 1972. This article will discuss how the teaching techniques and curriculum have evolved over the past four years.

UC Cooperative Extension has been working for four years with regional offices of the Bureau of Migrant Education and the California Mini-Corps to develop outdoor education programs for the children of migrant farm workers. Inquiry techniques and learn-by-doing activities were used to teach oral language with science as the vehicle.

Not available – first paragraph follows:
Some extremely dwarfed Eugenia cultivars have been developed a UCLA by Dr. V. Stoutemyer. Although none has been released yet for commercial propagation, plans call for making several of these cultivars available for this purpose as soon as necessary authorization secured.

Experiments showed that growth of the dwarf Eugenia plants was influenced by the soil mixture and that the use of GA3 was actually detrimental, considering the type of growth obtained. Whenever these plants are propagated and cultivated, a highly organic soil mixture should be used.

Not available – first paragraph follows:
Growers of tomatoes for the fresh market often report that there are more small tomatoes as the season progresses. The general feeling is that productivity is related to the ability to move adequate irrigation water into the soil. Preliminary studies a t the Lindcove Field Station in 1973 and 1974 indicate that yield and size of fresh market tomatoes are indeed influenced when soil penetration by furrow-applied water is reduced. A soil surface that is constantly moist from frequent water addition while daily picking is going on leads to soil compaction by harvest laborers walking over the moist soil. Reduced water penetration may lead to increased frequency of irrigation, further compounding the problem.

Growers of fresh market tomatoes frequently attribute an increase in small fruit during the growing season to poor water relations. In studies on a Vista sandy loam soil, greater numbers of small fruit were produced by drought-stressed plants. A high frequency of furrow irrigation caused the soil surface to "seal" greatly restricting water penetration and lowering the production of large tomatoes. Production was best when water was added through a drip hose placed at the base of plants in the row or by less frequent furrow irrigation.

Not available – first paragraph follows:
Water penetration slows during the growing season in furrowirrigated, fresh market tomato fields on eastern San Joaquin Valley soils. Such slowing has been shown also in preliminary experiments a the Lindcove Field Station in 1973 and 1974. In 1975, an experiment was conducted at the Lindcove Field Station, on a Vista sandy loam soil, to examine the influence of furrow irrigation frequency on surface penetration capability, and to determine whether drip irrigation (trickle) could maintain adequate water penetration throughout the season.

Frequent furrow irrigation of fresh market tomatoes, on a sandy loam soil, caused the soil surface to seal, greatly restricting water penetration into the plant root zone. Water penetration in furrows was adequate throughout the season if the frequency of irrigation was lowered. A drip irrigation system maintains not only a desirable soil moisture distribution, but also the cultural advantage of a dry surface area for foot traffic of harvesters that improves their efficiency and reduces soil compaction.

Not available – first paragraph follows:
It was observed in laboratory tests that additions of synthetic urea to the rearing medium killed larvae of the eye gnat, Hippelates collusor (Townsend). Mortality was direct through contact with this fertilizer. Therefore, field tests were conducted to test the effectiveness of urea against natural H. collusor populations and also against the biting gnat, Leptoconops kerteszi (Kieffed, which breeds in river bottoms and moist sandy soils in southern California.

Naturally breeding field populations of Hippelates eye gnats and Leptoconops biting gnats were reduced with granular and spray applications of urea to the soil. Control ranged from 10 to 96 percent depending on the dosage and application method (disced or surface-applied). Possible modes of action are mechanical abrasion of gnat larvae, and the favoring of fungal infections. The use of urea as a substance harmless to natural enemies may be beneficial in the integrated control of pestiferous soil arthropods.

Not available – first paragraph follows:
Approximately 2 million head of stocker and feeder cattle are shipped into the state of California annually. Depending on economic circumstances, one-fourth to onehalf of these animals are lightweight calves (350 pounds or less). Typically, 2 to 5 percent of these animals are lost due to death or as culls. These losses can cost California feedlots as much as $120 million annually.

In three preventive medication experiments at the UC Imperial Valley Field Station, oxytetracycline was administered orally and intramuscularly to calves with varying success in reducing cost per pound of gain. The presence of OTC in feed rations and water can reduce feed intake; intramuscular injections are costly but do not affect weight gain negatively.

Not available – first paragraph follows:
Powdery mildew of sugarbeet, caused by Erysiphe polygoni DC., was first reported in California in 1934 but did not become prevalent statewide until the 1974 season. Observations in Imperial County show wide differences in intensity of powdery mildew in various fields. In some sugarbeet fields many plants were completely covered with mildew while others had medium to light infestation of leaves. A question was raised as to whether it was necessary o treat every field in the valley for control of powdery mildew. To help answer this question a sulfur-dust airplane trial was initiated in the 1974-75 growing season.

Not available – first paragraph follows:
Powdery mildew of sugarbeet, caused by Erysiphe polygoni DC., was first reported in California in 1934 but did not become prevalent statewide until the 1974 season. Observations in Imperial County show wide differences in intensity of powdery mildew in various fields. In some sugarbeet fields many plants were completely covered with mildew while others had medium to light infestation of leaves. A question was raised as to whether it was necessary o treat every field in the valley for control of powdery mildew. To help answer this question a sulfur-dust airplane trial was initiated in the 1974-75 growing season.

Not available – first paragraph follows:
Variable susceptibility to rind necrosis in watermelon has been reported in Florida. The test reported herein was conducted to evaluate several watermelon cultivars for resistance to rind necrosis in a desert environment. Seed of seven cultivars was planted in February 1975, four feet apart in 25-foot-long beds. After emergence of plants the plots were thinned to one plant per hill or about six plants per plot. The plots were randomized and replicated six times. Ripe fruit was harvested on June 25, 1975 and examined for rind necrosis. Each fruit was sliced crosswise into 2- to 3-inch wide slices and checked for rind necrosis. At harvesting time the temperature of the fruit side that was exposed to the sun at a depth of 1½ inch was 127°F (52.7°C).

Rind necrosis is a perennial disorder of watermelon fruit in the Imperial Valley, California, which, on the average, causes about $100,000 loss each year. The disorder has also been reported in Hawaii, Texas and Florida. Bacteria have often been implicated as causal agents for rind necrosis. In this study, all cultivars were susceptible to rind necrosis.

Research articles

Not available – first paragraph follows:
Until recently, UC Cooperative Extension has addressed itself to all phases of agricultural production and processing but has virtually ignored the social problems of farm labor. For the past five years, however, with funding from the Expanded Nutrition Education Program (ENEP) and Community Resources Development (CRD), increasing emphasis has been given to this area. One of the first pilot programs implemented was to provide outdoor education for migrant children enrolled in summer schools in Region I, Office of Migrant Education. The program was initiated in the summer of 1972. This article will discuss how the teaching techniques and curriculum have evolved over the past four years.

UC Cooperative Extension has been working for four years with regional offices of the Bureau of Migrant Education and the California Mini-Corps to develop outdoor education programs for the children of migrant farm workers. Inquiry techniques and learn-by-doing activities were used to teach oral language with science as the vehicle.

Not available – first paragraph follows:
Some extremely dwarfed Eugenia cultivars have been developed a UCLA by Dr. V. Stoutemyer. Although none has been released yet for commercial propagation, plans call for making several of these cultivars available for this purpose as soon as necessary authorization secured.

Experiments showed that growth of the dwarf Eugenia plants was influenced by the soil mixture and that the use of GA3 was actually detrimental, considering the type of growth obtained. Whenever these plants are propagated and cultivated, a highly organic soil mixture should be used.

Not available – first paragraph follows:
Growers of tomatoes for the fresh market often report that there are more small tomatoes as the season progresses. The general feeling is that productivity is related to the ability to move adequate irrigation water into the soil. Preliminary studies a t the Lindcove Field Station in 1973 and 1974 indicate that yield and size of fresh market tomatoes are indeed influenced when soil penetration by furrow-applied water is reduced. A soil surface that is constantly moist from frequent water addition while daily picking is going on leads to soil compaction by harvest laborers walking over the moist soil. Reduced water penetration may lead to increased frequency of irrigation, further compounding the problem.

Growers of fresh market tomatoes frequently attribute an increase in small fruit during the growing season to poor water relations. In studies on a Vista sandy loam soil, greater numbers of small fruit were produced by drought-stressed plants. A high frequency of furrow irrigation caused the soil surface to "seal" greatly restricting water penetration and lowering the production of large tomatoes. Production was best when water was added through a drip hose placed at the base of plants in the row or by less frequent furrow irrigation.

Not available – first paragraph follows:
Water penetration slows during the growing season in furrowirrigated, fresh market tomato fields on eastern San Joaquin Valley soils. Such slowing has been shown also in preliminary experiments a the Lindcove Field Station in 1973 and 1974. In 1975, an experiment was conducted at the Lindcove Field Station, on a Vista sandy loam soil, to examine the influence of furrow irrigation frequency on surface penetration capability, and to determine whether drip irrigation (trickle) could maintain adequate water penetration throughout the season.

Frequent furrow irrigation of fresh market tomatoes, on a sandy loam soil, caused the soil surface to seal, greatly restricting water penetration into the plant root zone. Water penetration in furrows was adequate throughout the season if the frequency of irrigation was lowered. A drip irrigation system maintains not only a desirable soil moisture distribution, but also the cultural advantage of a dry surface area for foot traffic of harvesters that improves their efficiency and reduces soil compaction.

Not available – first paragraph follows:
It was observed in laboratory tests that additions of synthetic urea to the rearing medium killed larvae of the eye gnat, Hippelates collusor (Townsend). Mortality was direct through contact with this fertilizer. Therefore, field tests were conducted to test the effectiveness of urea against natural H. collusor populations and also against the biting gnat, Leptoconops kerteszi (Kieffed, which breeds in river bottoms and moist sandy soils in southern California.

Naturally breeding field populations of Hippelates eye gnats and Leptoconops biting gnats were reduced with granular and spray applications of urea to the soil. Control ranged from 10 to 96 percent depending on the dosage and application method (disced or surface-applied). Possible modes of action are mechanical abrasion of gnat larvae, and the favoring of fungal infections. The use of urea as a substance harmless to natural enemies may be beneficial in the integrated control of pestiferous soil arthropods.

Not available – first paragraph follows:
Approximately 2 million head of stocker and feeder cattle are shipped into the state of California annually. Depending on economic circumstances, one-fourth to onehalf of these animals are lightweight calves (350 pounds or less). Typically, 2 to 5 percent of these animals are lost due to death or as culls. These losses can cost California feedlots as much as $120 million annually.

In three preventive medication experiments at the UC Imperial Valley Field Station, oxytetracycline was administered orally and intramuscularly to calves with varying success in reducing cost per pound of gain. The presence of OTC in feed rations and water can reduce feed intake; intramuscular injections are costly but do not affect weight gain negatively.

Not available – first paragraph follows:
Powdery mildew of sugarbeet, caused by Erysiphe polygoni DC., was first reported in California in 1934 but did not become prevalent statewide until the 1974 season. Observations in Imperial County show wide differences in intensity of powdery mildew in various fields. In some sugarbeet fields many plants were completely covered with mildew while others had medium to light infestation of leaves. A question was raised as to whether it was necessary o treat every field in the valley for control of powdery mildew. To help answer this question a sulfur-dust airplane trial was initiated in the 1974-75 growing season.

Not available – first paragraph follows:
Powdery mildew of sugarbeet, caused by Erysiphe polygoni DC., was first reported in California in 1934 but did not become prevalent statewide until the 1974 season. Observations in Imperial County show wide differences in intensity of powdery mildew in various fields. In some sugarbeet fields many plants were completely covered with mildew while others had medium to light infestation of leaves. A question was raised as to whether it was necessary o treat every field in the valley for control of powdery mildew. To help answer this question a sulfur-dust airplane trial was initiated in the 1974-75 growing season.

Not available – first paragraph follows:
Variable susceptibility to rind necrosis in watermelon has been reported in Florida. The test reported herein was conducted to evaluate several watermelon cultivars for resistance to rind necrosis in a desert environment. Seed of seven cultivars was planted in February 1975, four feet apart in 25-foot-long beds. After emergence of plants the plots were thinned to one plant per hill or about six plants per plot. The plots were randomized and replicated six times. Ripe fruit was harvested on June 25, 1975 and examined for rind necrosis. Each fruit was sliced crosswise into 2- to 3-inch wide slices and checked for rind necrosis. At harvesting time the temperature of the fruit side that was exposed to the sun at a depth of 1½ inch was 127°F (52.7°C).

Rind necrosis is a perennial disorder of watermelon fruit in the Imperial Valley, California, which, on the average, causes about $100,000 loss each year. The disorder has also been reported in Hawaii, Texas and Florida. Bacteria have often been implicated as causal agents for rind necrosis. In this study, all cultivars were susceptible to rind necrosis.